Catalyzes the initial reaction in O-linked oligosaccharide biosynthesis, the transfer of an N-acetyl-D-galactosamine residue to a serine or threonine residue on the protein receptor. Does not glycosylate apomucin or SDC3.
Specifically expressed in brain. Not expressed in heart, placenta, lung, liver, skeletal muscle, kidney, pancreas, spleen, thymus, prostate, testis, ovary, small intestine, colon and leukocyte. In brain, it is expressed in cerebellum, frontal lobe, temporal lobe, putamen and spinal cord, weakly expressed in cerebral cortex. Not expressed in medulla and occipital pole.
Protein modification; protein glycosylation.
Belongs to the glycosyltransferase 2 family. GalNAc-T subfamily. Contains 1 ricin B-type lectin domain.
There are two conserved domains in the glycosyltransferase region: the N-terminal domain (domain A, also called GT1 motif), which is probably involved in manganese coordination and substrate binding and the C-terminal domain (domain B, also called Gal/GalNAc-T motif), which is probably involved in catalytic reaction and UDP-Gal binding. The ricin B-type lectin domain binds to GalNAc and contributes to the glycopeptide specificity.